Gmail Purging

[trunolimit]

Hello Forum,

My Gmail has become completely unmanageable. I've got over 3,000 unread emails. I'd like to completely delete all my emails except for a couple.

What is the easiest way to do this through the web? I can only display 100 emails at a time and I don't feel like clicking through 30+ pages of emails. I was thinking maybe there is a fancy filter I can use to trash all emails except a couple with special labels.

I'd like to avoid installing an email client but if it's the only way, which client is the most awsomest?